Generally described, computing devices and communication networks can be utilized to exchange content and other information. In a common application, a computing device can generate content to be distributed to other computing devices via a communication network. For example, a user of a computing device, such as a personal computer, laptop computer, tablet computer, or smart phone, may use the computing device to create content, such as text, documents, audio recordings, video, images, animations, and the like. The content may be transmitted directly to other users' computing devices, or the content may be transmitted to a network-accessible content server for distribution to other users' computing devices.
In some scenarios, a user may generate content by entering text and attaching or transmitting media files related to the text in some way. For example, a user may create an email message with textual content in the body of the email, and images attached to the email. As another example, a user may create an article or post to be made available to other users via the Internet. The article or post may include textual content, and may also have images, videos, and the like embedded within the text or otherwise displayed along with the text.
From the perspective of a user generating content, a user experience can be defined in terms of the performance and latencies associated with creating the content, transmitting the content to server computing devices for distribution, or transmitting the content to other user computing devices. For example, content creation may be performed in a step-by-step process, with a user first creating the text portion of the content, then adding images to the content, and finally submitting the content for distribution by a content server. In this process, a user transmitting content to a content server may have a better experience when transmitting the content to the content server over a wired network connection or WiFi connection than when transmitting content over slower wireless networks, such as 3G/4G cellular networks.